This article, published by the National Education Association, claims that the block schedule (A/B days with 80-90 min classes) is more beneficial to high school students' psyche as it allows for more flexibility in their school day. Traditionally, high school students stuck to a the same schedule every day with multiple classes and 40-50 min class times.
"Pope says a block schedule creates a "saner school day" by slowing down the pace, reducing homework and freeing up more time for hands-on learning and collaboration"